So I decided to try and make my own files after reading about it in On Divers Arts by Theophilus. Theophilus states "
...smear them with old pig fat and wrap them around with leather strips cut from goat skin and bind them with linen thread. After this cover them individually with kneaded clay, leaving the tangs bare. When they are dried, put them in the fire, blow vigorously, and the goat skin will be burnt." I also found a link to a paper from some other people that had also tried it and that was very helpful, learning from their mistakes! (do a google search for mastermyr fynd file.doc) There was also a video on YouTube showing someone cutting the teeth on a file that had some good tips. I didn't get any pictures of forging and cutting the teeth, I will try to do that when I make some more files. I did not follow the recipe exactly from Theophilus, I didn't have any goat leather, just cow, and I used a mixture of clay and horse dung like the people from the Mastermyr project did, which Theophilus uses in other recipies for casting and building a forge.
Here are the files already covered in pig fat, and tied up in leather with sisal rope.
Files are covered in a mixture of clay and horse shit (yay) and left to dry overnight. The shit really binds everything together very well and there was no problem with cracking when put into the fire the next day, even though they were not completely dry.
I warmed them slowly, thinking that the clay would flake off, but it held together quite well. You can see flames jetting out the end of one of them as the leather and fat start to burn inside.
From what I have read of carbonising metal, the longer it stays in the fire the better it will work, Theophilus doesn't say exactly how long they should stay there. I had them glowing orange to yellow for about 15 minutes until I noticed that the clay had flaked off the tip of one of them, so I removed them from the fire and quenched them. (Theophilus states that I should have broken the clay off first then quenched...maybe it has to do with the steam (and evil smell) that jetted out the end??)
The clay dung mixture fired like a glazed clay, very glass like. You can see the tip of the file sticking out of the top one. The metal looks a little burned/melted there.
Here they are after I smashed the clay off. One of them had warped a little but it was easy to straighten out. I was very surprised when I tried them on mild steel, they worked just fine and the teeth stayed sharp. (they are mild steel as well, I intend to make some more out of wrought iron when I try next)
Here they are with some handles added. I really got to try one of these out a lot while working on the clock gear for the second clock I am making. It just happened to be exactly the right width to fit between the teeth, so I filed all 72 gear teeth with it. I did notice some dulling, but not much, and that the edge of the file wasn't exactly square, so I had to file from both directions to even things up.
I cant wait to try this again with some wrought iron that I have been scavenging.
